This research is concerned primarily with certain endogenous potentials of the brain which can be recorded from the scalp of human subjects. The major objectives include: 1. Determining whether some endogenous potentials, which have been inconstantly observed, can be reliably identified. 2. Clarifying essential questions concerning the functional significance of specific endogenous potentials. 3. Analyzing differences in scalp distribution of endogenous potentials as a function of requiring semantic as opposed to purely sensory discriminations. 4. Using the method of divided attention to examine the effect of alterations in the allocation of attention among various psychological processes upon endogenous as well as exogenous potentials.